Electroplating is commonly used in integrated circuit manufacturing processes to form electrically conductive structures. For example, in a copper damascene process, electroplating is used to form copper lines and vias within channels previously etched into a dielectric layer. In such a process, a seed layer of copper is first deposited into the channels and on the substrate surface via physical vapor deposition. Then, electroplating is used to deposit a thicker copper layer over the seed layer such that the channels are completely filled. Excess copper is then removed by chemical mechanical polishing, thereby forming the individual copper features.
Current electroplating systems may be classified as “open contact” and “closed contact.” Open contact plating systems are systems in which the wafer contacts that deliver electric current to the seed layer during plating are exposed to the plating solution. Likewise, closed contact plating systems are those in which the contacts are not exposed to the plating solution.
When fabricating integrated circuits, it is generally desirable to utilize as much wafer surface as possible for the fabrication of devices to increase a quantity of devices per wafer. However, electroplating systems generally utilize electrical contacts and other structures that contact the wafer during deposition, and therefore limit an amount of surface area that can be plated. For example, in open contact plating systems, because the electrodes are exposed to the plating solution during a plating process, the electrodes are plated to the substrate surface during the process. Removal of the electrodes exposes unplated regions where the electrodes contacted the substrate. Further, removal of the contacts may cause damage to the copper layer in the vicinity of the electrodes, rendering, for example, 2 mm or more of the outer perimeter of the wafer unsuitable for integrated circuit fabrication.